Electric resistance heating assembly

ABSTRACT

An electric resistance heating assembly suitable for insertion in a furnace. The assembly includes a resistance heating element consisting of a material which is plastically deformable at its operating temperature. The heating element is in the form of elongated members which are mounted substantially horizontally. The assembly further includes a heat resistant carrier which is capable of supporting the heating element at several points along substantially its entire length in such a way that the heating element is substantially free radiating. The assembly, comprising the heating element and the supporting carrier is mountable as a unit in the furnace or other area to be heated.

United States Patent IHI 3,595,978

[72] Inventors Erik Stenlora;

Evert Malia: Bengt Magnum, all of lhllstahlnimar, Sweden [2| Appl No. 855.657 [22] Filed Sept. 5, 1969 [4S] Patented July 27, I971 [73] Assignee Aktiebolaget Knnthal Hallstatt-lunar, Sweden [54] ELECTRIC RESISTANCE HEATING ASSEMBLY 14 Claims, 2 Drawing Figs.

[52] U.S.Cl 13/25, 338/315 [51] lnLCl .7 H05b3/l2 [50] Field Search 13/25; 338/304, 315, 290. 305. 316. 321

[56} References Cited UNITED STATES PATENTS 2,913,695 I 1/1959 Borghult, et al. 13/25 X FOREIGN PATENTS 345,874 4" 93l Great Britain. 881,976 7/1953 Germany.

Primary Examiner-Harold Broome Assistant Examiner-R. N. Envall. Jr. Attorney-Brumbaugh, Graves, Donohue & Raymond ABSTRACT: An electric resistance heating assembly suitable for insertion in a furnace. The assembly includes a resistance heating element consisting of a material which is plastically deformable at its operating temperature. The heating element is in the form of elongated members which are mounted substantially horizontally. The assembly further includes a heat resistant carrier which is capable of supporting the heating element at several points along substantially its entire length in such a way that the heating element is substantially free radiating. The assembly, comprising the heating element and the supporting carrier is mountable as a unit in the furnace or other area to be heated.

ELECTRIC RESISTANCE HEATING ASSEMBLY BACKGROUND OF THF. INVENTION The present invention relates to an electric resistance heating assembly suitable for insertion, as a unit, in a furnace or the like.

More particularly, the present invention relates to an electric resistance heating assembly which employs a resistance heating element of the kind consisting of a material which is plastically deformable at its operating temperature.

Some electric resistance heating elements, such as those sold in the United States under the registered trademark KANTHAL SUPER -i.e., elements which consist substantially of MoSi,become so soft at their operating temperature that they may become deformed by their own weight. Difficulties have arisen when attempting to support such heating elements, due to their deformable properties, especially when the elements are to be mounted on a horizontal plane.

SUMMARY OF THE INVENTION An object of the present invention, therefore, is to provide a device for use with electric resistance heating elements of the above-described type, which renders possible a horizontal mounting of the elements despite their softness at high tempe ratures.

This object, as well as other objects which will become apparent in the discussion that follows, is achieved, according to the present invention, by providing each heating element with a heat resistant carrier which forms, with the heating element, a heating assembly mountable as a unit. The carrier, according to the present invention, is adapted to support the heating element at several points along substantially its entire length in such a way that the heating element is substantially free radiating.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an elevational view of the electric resistance heat ing assembly according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the plane ll-ll of FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT By way of example only, a preferred embodiment of the electric resistance heating assembly according to the present invention will now be described in connection with FIGS. 1 and 2 ofthe drawing.

FIG. I of the drawing shows a substantially U-shaped re sistance heating element (only one limb of which is shown) which is introduced through a furnace wall I! shown in section. The heating element is supplemented by a carrier I2 of hightemperature resistant material, such as a tube of silicon carbide. The carrier is provided with a plurality of suspension members, seven in this case, in the form of omega-shaped bodies 13. The shape of the suspension members is best shown in FIG. 2. In this case, the suspension members are loosely slipped over the tubular carrier I2. The carrier 12 is secured to a lead-in brick I4 through which also the two lead-in supply conductors 10A of the heating element 10 are introduced in such a way that they are accessible for connection outside the furnace wall. Outside the lead-in brick [4 there is provided a slightly larger lead-in brick IS through which the conductors IOA likewise extend.

It is apparent that the device according to the invention constitutes a unit, meaning that the assembly ofthe resistance heating element I0 with its carrier means 12, I3, possibly also with the lead-in bricks I4, 15, may be introduced through the furnace wall and replaced as a unit in such a way that the heating element can then operate in horizontal position. A sagging of the heat-softened resistance heating element is prevented by the carrier means l2, 13 which consist of a material resistant to the operating temperature or of a combination of suitable materials.

The carrier I2 may, for instance, be made of recrystallized silicon carbide or ofa highly heat resistant oxidic material. In case the carrier consists of recrystallized silicon carbide, it conveniently also contains MoSi as pore filler. The suspen sion members I3 conveniently consist ofa heat resistant elcctrically insulating material, such as sillimanite.

As appears from FIG. 2, the suspension members l3 have, in this case, the form ofomega-shaped members on the feet of which the Ushaped element is supported. To ensure the required static stability, the suspension members have their center of gravity and the supporting points for the element I0 located at a safe distance below the horizontal carrier 12.

It will be appreciated that various modifications and changes can be made in the electric resistance heating assembly of the present invention without departing from the essence of the invention.

We claim:

I. An electric resistance heating assembly comprising, in combination:

a. resistance heating element means consisting of a material which is plastically deformable at its operating temperature and being in the form of elongated members which are mounted substantially horizontally;

b. elongate heat resistant carrier means for supporting said heating element means at several points along substantially its entire length in such a way that said heating ele ment is substantially free radiating, said carrier means being mountable at least one end thereof so that the entire portion thereof which supports the incandescent zone of said heating element means is freely suspended;

whereby said heating element means and said heat resistant carrier means form an electric resistance heating assembly which is mountable as a unit.

2. The heating assembly defined in claim I, wherein said carrier means includes:

l. elongated support means having a circular cross section;

and

2. a plurality of suspension members for suspending said heating element means from said support means.

3. The heating assembly defined in claim 2, wherein said suspension members surround at least a portion of said support means, thereby to suspend themselves from said support means.

4. The heating assembly defined in claim 3, wherein said suspension members are movably mounted on said support means and wherein the center of gravity of said suspension members and the points at which said suspension members support said heating element are located below said support means.

5. The heating assembly defined in claim 2, wherein said support means consists of an oxidic material resistant to high temperatures.

6. The heating assembly defined in claim 2, wherein said support means consists of recrystallized silicon carbide.

7. The heating assembly defined in claim 6, wherein said support means contains MoSi as a pore filler.

8. The heating assembly defined in claim 2, wherein said suspension members consist ofa heat resistant and electrically insulating material.

9. The heating assembly defined in claim 8, wherein said suspension members consist of sillirnanite.

It]. The heating assembly defined in claim 2, wherein said support means comprises a straight tube and wherein said suspension members are substantially omega-shaped,

whereby said suspension members are suspended from said support means by the upper circular portion of the omega shape and support said heating element means by the lower feet portion ofthe omega shape.

11. The assembly defined in claim 2, further comprising brick means, suitable for insertion in the wall ofa furnace, attached to the base of said support means.

arranged substantially in parallel with the longitudinal axis of said carrier means and wherein said carrier means includes elongate support means and a plurality of suspension members distributed along said support means for suspending the incandescent zone of said heating element means from said support means at a plurality of points along said zone. 

1. An electric resistance heating assembly comprising, in combination: a. resistance heating element means consisting of a material which is plastically deformable at its operating temperature and being in the form of elongated members which are mounted substantially horizontally; b. elongate heat resistant carrier means for supporting said heating element means at several points along substantially its entire length in such a way that said heating element is substantially free radiating, said carrier means being mountable at at least one end thereof so that the entire portion thereof which supports the incandescent zone of said heating element means is freely suspended; whereby said heating element means and said heat resistant carrier means form an electric resistance heating assembly which is mountable as a unit.
 2. The heating assembly defined in claim 1, wherein said carrier means includes:
 2. a plurality of suspension members for suspending said heating element means from said support means.
 3. The heating assembly defined in claim 2, wherein said suspension members surround at least a portion of said support means, thereby to suspend themselves from said support means.
 4. The heating assembly defined in claim 3, wherein said suspension members are movably mounted on said support means and wherein the center of gravity of said suspension members and the points at which said suspension members support said heating element are located below said support means.
 5. The heating assembly defined in claim 2, wherein said support means consists of an oxidic material resistant to high temperatures.
 6. The heating assembly defined in claim 2, wherein said support means consists of recrystallized silicon carbide.
 7. The heating assembly defined in claim 6, wherein said support means contains MoSi2 as a pore filler.
 8. The heating assembly defined in claim 2, wherein said suspension members consist of a heat resistant and electrically insulating material.
 9. The heating assembly defined in claim 8, wherein said suspension members consist of sillimanite.
 10. The heating assembly defined in claim 2, wherein said support means comprises a straight tube and wherein said suspension members are substantially omega-shaped, whereby said suspension members are suspended from said support means by the upper circular portion of the omega shape and support said heating element means by the lower feet portion of the omega shape.
 11. The assembly defined in claim 2, further comprising brick means, suitable for insertion in the wall of a furnace, attached to the base of said support means.
 12. The assembly defined in claim 11, wherein said support means is made integral with said brick means.
 13. The heating assembly defined in claim 2, wherein said suspension members include a horizontal crossmember for supporting said heating element means.
 14. The heating assembly defined in claim 1, wherein said heating element means is mounted with its longitudinal axis arranged substantially in parallel with the longitudinal axis of said carrier means and wherein said carrier means includes elongate support means and a plurality of suspension members distributed along said support means for suspending the incandescent zone of said heating element means from said support means at a plurality of points along said zone. 